Depth-perception radiography

ABSTRACT

The invention described and claimed herein is a method and apparatus for producing a picture of an opaque three-dimensional subject in which the picture conveys to the unaided eyes of the observer the true spatial relationship of the internal and external elements of the subject. Specifically, the invention provides for relative rotation between a subject and the combination of a radiation source and plane transducer to produce photographic light that is scanned through a narrow aperture across a displacement grid in front of a film plane. The foregoing produces a photograph that upon direct viewing through the displacement grid conveys full internal well will as external depth perception.

v Umted States Patent 1 3,560,740

[72] Inventor Russell Maurice Tripp FOREIGN PATENTS Saramga, Calif-449,213 6/1936 Great Britain 250/6] [2]] Appl No. 565,227 [22] FiledJuly 4 1966 Pnmary Examiner-William F. Llndqulst [45] Patented Feb 2,1971 Attorney-Gregg & Hendricson [73] Assignee Tripp ResearchCorporation Saratoga, Calif. a corporation of Delaware 5DEPTH-PERCEPTION RADIOGRAPHY ABSTRACT: The invention descrihed andclaimed herein iS a 14 Claims 3 Drawing Figg method and apparatus forproducing a picture of an opaque three-dimensional subject in which thepicture conveys to the U.S. id d eyes f th observer th t tialrglationship of 250/65 the internal and external elements of thesubject. Specifically, [5] Int. Cl Goln 23/04 the invention provides forrelative rotation between a bj 37/22 and the combination of a radiationsource and lane trans- [50] F ldof Search 250 l p le l6 65 ducer toproduce photographic light that is scanned h h a [561 References CMSE522%?22225352135???if?i h lh i iii-1'31 e p og ap a upo l UNITEDSTATES PATENTS viewing through the displacement grid conveys fullinternal 2,492,520 l2/l949 Bonnet 250/61X as Well as external depthperception.

. 1 nsr'ru-rsncnr'rlou asprocmnv The present invention relates ingeneral to method and apparatus for producing photographsof.three-dimensional objects which may be opaque to visiblelight; andoperates in such a manner as to make it possible for an observer toperceive the spatial relation between various points throughout theobject, asthough he were viewing a transparent threedimensional model ofthe object. The present invention produces a two-dimensional picturethat need only be-viewed with the unaided eye; and, such picture differsfrom the usual stereoscopic photographs in that when the viewer scansthe picture there is observed a changing parallax effect, just as thoughthe original three-dimensional object were being scanned rather than atwo-dimensional projection thereof. In the following description of thepresent invention, the term .fradiographyis taken in its broadest senseto mean the production of radiographs by any suitable type ofpenetrating radiation as set forth below and is in no way limited tox-rays.

The art of closely related stereoscopic photography is quite old; and,more recently, this art has been applied to x-ray photography,particularly in the field of dentistry. Following early work by H. E.Ives, disclosed in part of U. S. Pat. No. 1,916,320, considerableadvances were made in the field by M. Bonnet, as disclosed and claimed,for example, in U. S. Pat.

No. 2,506,131 and U. S. Pat. No. 2,492,520. it is taught by Bonnet thata selectograph and light-sensitive plate shall be rotated simultaneouslywith an object to be photographed; and, various mechanisms have beendisclosed by both Bonnet and subsequent workers in the field foraccomplishing the desired motions. Certain of these subsequentdevelopments are disclosed and claimed in U. S. Pat. No. 2,521,154 toDudley, in U. S. Pat. No. 2,684,446 to Paatero and U. S. Pat. No.3,045,118 to l-lollman et al. An interesting alternative approach to theproblem is presented in U. S. Pat. No. 3,106,640 to Oldendorf; and,in'addition, numerous advances in the general field have been providedby Winnek, as exemplified in ,U. S. Pat. No. 2,562,077. Theaforementioned prior art workers have materially advanced the state ofthe art; but, to date, there apparently remains to be developed a trulypractical three-dimensional process and apparatus for depicting thespatial relationship of internal portions of an opaque object.

The present invention does provide a truly practical process andapparatus embodying much of the teaching of the prior art,'asexemplified above, by incorporating certain highly important limitationsand improvements which extend the art to the point of true practicalityfor widespread application and utilization. The present invention is inno way limited to the utilization of x-rays; but, instead, is applicablewith any type of penetrating radiation that is, in part, attenuated oraffected by a three-dimensional object to be examined, with suchattenuation or affect being proportional to the path length through theobject and the chemical or physical properties of the material.Furthermore, the present invention is in no way limited to utilizationupon human objects, but is equally applicable for all types ofindustrial testing as, for example, in the detection of casting flaws orthe like.

e In brief, the present invention employs a source of radiant energy orpenetrating particles having the property of being ducer surfacedisposed approximately normal to the axis of propagation of the radiantenergy for intercepting such energy or particles after they. havetraversed the subject, and producing actinic energy from an output faceof the transducer. The intensity of actinic energy or photographic lightemerging from each point on the output face of the transducer isproportional to the incident energy at each and every correspondingpoint upon the input surface of the transducer. The invention, inaddition, provides for a permanent recording of the relative intensityof energy distribution over the two-dimensional surface of a transducerat successive instants in such a manner that the instantaneous magnitudeof intensity at any point be determined at some later time independentlyof the magnitude of the intensity at other instants during therecording. More specifically, the invention provides for photographingthrough a narrow slit aperture which is changing its position relativeto the recording surface such that the normal from the aperture to therecording surface is changing its angle of incidence to the recordingsurface synchronously with the changing display in the transducer outputscreen. Furthermore, the recording surface consists of a photographicemulsion applied to the backside of the film base which has the frontside thereof embossed, preferably with parallel cylindrical lenses,although parallel prisms or closely spaced spherical lenses may beemployed. The lenses or prisms affect refraction of the light fallingthereon to a particular portion of the sensitive emulsion, and thelocation of such portion is dependent upon the angle of incidence of theray from the slit aperture to the film surface. As the angle ofincidence changes during a recording, the instantaneous line imagebehind each prism or lenticulation is displaced laterally, and,therefore, does not interfere with the previously recorded data. In thepreferred instance where the front side of the film is embossed I withlenses, they will focus an image of the slit aperture onto the emulsionsurface. It is to be appreciated that the subject being photographed isrotated during photography so as to present differing radiation patternsupon the input face of the transducer. 1n the majority of applicationsthe invention provides for relative rotation between the subject and theportion of the apparatus including the source of radiation and trans 1aperture is sufficiently large to have the effect of supplying the lightrays simultaneously across the full acceptance angle of the embossedlenticulations, then the full width of emulsion surface behind eachlenticulation is exposed to each relative position of the aperture withrespect to the recording film, and there remains no unexposed surface torecord succeeding instantaneous images appearing on the transduceroutput screen at a later instant-The successful practice of the presentinvention, therefore, necessitates employinga very small aperture, butin doing so, the light-gathering effectiveness is greatly reduced; and,in some cases this may mean that in order to obtain sufficient exposureto produce a readable picture, the subject must absorb an excessiveamount of radiation. In medical diagnostic radiology, for example, thepatient exposed to x-rays may absorb more damaging radiation than whatis considered a safe, allowable dosage.

In order to overcome the above-noted difficulty, the present inventionemploys a camera in which the usual disc aperture is replaced by a slitaperture having the same width as the appropriate disc diameter, but amuch greater light-transmission area; and, furthermore, the presentinvention provides for improving the overall efficiency with which, theincident energy is absorbed and converted, to actinic energy andintensified. Such an improvement in transducing may be accomplished bymeans such as the x-ray transducer disclosed and claimed in my copendingpatent application Ser. No. 399,792, filed in the U. S. Pat. Off. onSept. 28, 1964 now abandoned.

According to the present invention, the procedure to recorddepth-perception photographs of a three-dimensional object which isopaque to light is accomplished by casting a changing shadowflof thethree-dimensional object onto a two-dimensional surface by relativerotation of the subject and the radiation source-projection surfacecombination (the latter of which are rigidly fixed with respect to oneanother). The changing shadowfimage is photographed by a camera having aslit aperture that is parallel to the axis of cylindrical lenticulationsembossed on the film face opposite the emulsion. The narrow beam oflight from the slit aperture is refracted by the embossed lenticulationsand focused onto narrow strips of emulsion behind the lenticulations ata position determined by the angle of incidence from the aperture to thefilm plane. By varying the angle of incidence synchronously with therate of change of the image on the projection surface, the continuoussuccession of changing images are displaced laterally rather thanfalling one on top the other, so as to preclude the blurring that wouldotherwise result. When the resultant photograph is viewed through theside with the embossed lenticulations, and with the axis of thelenticulations vertically disposed, each eye of the viewer will see theparticular image on the film corresponding to the angle of incidencethat the eye makes with the film. The lenticulation, in turn, willmagnify the elementary strip exposure to fill the entire lenticulationwidth and match with the corresponding exposure elements behind theadjacent lenticulations. When the observer's eyes scan the photograph soas to change the angle of incidence the line-ofsight makes with thephotograph, different views will be perceived by both eyes and since theline-of-sight from each eye is slightly different, the images on eachretina will be slightly different and the condition of retinal disparityfor producing depth perception is satisfied.

The present invention is illustrated, both as to method and apparatus,in the accompanying drawing wherein:

FIG. I is a schematic illustration of one embodiment of the presentinvention;

FIG. 2 is a partial schematic illustration of the lens and film end ofan alternative embodiment of the present invention;

FIG. 3 is a schematic illustration of yet another embodiment of thepresent invention.

Considering first the method of the present invention, there is employeda source of penetrating radiation disposed on one side of a relativelyopaque subject to be photographed. The radiation employed herein iscapable of passing through the subject while being affected by suchpassage, either in the manner of attenuation, diffusion or the like inrelation to the radiation path length through the object and chemical orphysical properties of the subjects or portions thereof. n the oppositeside of the subject there is provided a transducer for intercepting theradiant quanta passing through the object, and for producing actinicphotons therefrom. Commonly, this transducer produces a visible light,but the light may be of any wavelength most suitable for recording.Radiation incident upon one side of the transducer produces actinicradiation from the other side thereof in proportion at each pointthereon to the intensity of incident radiation. It will be appreciatedthat the visible or actinic light emanating from the transducer travelsoutwardly from each point thereon in diverging rays; and the presentinvention operates to mask out or block all but a selected beam of thislight which can pass through a narrow slit. The restricted beam of lightdiverging through the narrow slit is caused to impinge upon thelenticulations at the tilm plane with a continuously varying angle ofincidence. The light falling on the lenticulations, in addition to beingfocused into a thin line on the sensitive emulsion behind each of thelenticulations, is refracted laterally by an amount dependent upon theinstantaneous angle of incidence of the beam on the lenticulations. Thisprogressive lateral displacement of the line image across the emulsionarea behind each lenticulation makes possible the sequential recordingof a changing scene without the successive instantaneous imagesinterfering. The progressive lateral displacement of the line images inthe emulsion can be accomplished by lateral translation of a slitaperture between the camera objective and photographic medium, asexplained in more detail below, by lateral translation and rotation ofthe camera objective and slit aperture as a rigid unit, or may also beaccomplished by rotating the plane of the photographic film about anaxis corresponding to one of the cylindrical lenticulations whileobjective and aperture remain fixed. In all instances there occurs somerelative motion between the subject and the rigidly rc' latcd source ofradiation and transducer input surface. so that a changing view of thesubject is appearing on the transducer output. There are certainadvantages to be achieved by each of the above schemes for varying theangle of incidence of the light from the aperture onto the recordingfilm, but the obtaining of a successful photograph havingdepth-perception characteristics is dependent in all cases on employingan aperture which subtends a very small angle at the film plane.

Considering now particular preferred embodiments of the apparatus of thepresent invention, reference is made to FIG. I of the drawing whereinthere is illustrated the radiation source 11 disposed on one side of asubject 12 to be photographed, and directing penetrating radiation I3thereon. The source 11 may produce energy that is sonic, ultrasonic,visible light, ultra-violet light, infra-red, radio frequencyemanations. x-rays, gamma rays, nuclear particles and the like. Thesubject 12 is neither totally transparent nor totally opaque to theradiation I3 which is being employed, and the three-dimensional subject12 partially absorbs, attenuates, diffuses, dissipates or alters onpassing therethrough the radiation, such that the emergent radiation,after passage through the object, has the energy thereof affected inproportion to the path length traversed and the chemical or physicalproperties of the subject in the path of radiation. Immediately on theopposite side of the subject from the source ll there is disposedtransducer 14 which intercepts the energy or particles after they havetraversed the subject; and, while detecting the relative intensity ofenergy received at each point on the surface thereof, transforms thisenergy so detected into photographic light. The transducer 14 may alsointensify the energy in the form of light, so as to maximize theintensity of light emanating from the opposite side of transducer 14. Inthis respect it is noted that one of the prior art difficulties inapplying techniques of this sort to medical radiography was thedifficulty of obtaining sufficient light to adequately exposephotographic film without overexposing the subject to damagingradiation. C crtain prior art approaches to this problem have involvedthe utilization of wide-aperture photography which. however, in part,defeats the purpose in that successive instantaneous images are notindividually retrievable.

In accordance with the present invention, and, again, as illustrated inFIG. I, there is provided a film plate 16 or the like which may be ofconventional composition and which is provided on the surface facing thecamera objective with lenses or prisms capable of refracting the lightfalling thereon in a lateral direction depending upon the angle ofincidence of the light ray from the objective aperture to the filmplane, thereby permitting a continuous succession of images to berecorded by changing the angle of incidence and without interferencebetween successive images. This front surface 17 may take the form ofsmall parallel cylindrical lenses, parallel prisms or closely spacedspherical lenses. With cylindrical lenses or lenticulations only a smallportion of the cylindrical circum ference is employed in eachlenticulation. The radius of curvature and the arc width is determinedby well-known laws of geometrical optics relating radius of curvature,index of refraction, film thickness and f/number of camera objective. Ingeneral, this surface is illustrated in FIG. I as a lenticulatedsurface, and the entire photosensitive media, including the embossedsurface, is herein denominated by the numeral I8. It is to beappreciated that the lenticulations 17 or the like of the photographicmedium serve to focus the light impinging thereon to a line of light onthe film itself behind the lenticulation. Consequently, it may beconsidered that the front surface or lenticulations of the photographicmedium comprises a displacing grid.

In accordance with the present invention, the provision is made forvarying the angle of incidence with which light strikes the grid orlenticulations; and, this variation is synchronized with the changingview that appears in the transducer output face. Consequently,successive instantaneous views are recorded in juxtaposition or as acontinuously varying image upon the film. As shown in FIG. 1, there isprovided an objective lens 21 mounted together with and in front of aplate 22 having a slit aperture 23 therein. The objective lens 21 andplate 22, together with support structure, is herein formed as amoveable element 24 mounted for controlled translation laterally acrossthe path of light from the transducer 14 to the photographic medium 18.This translation may be accomplished manually or by a power source suchas a small electric motor 26 operating a rack and-pinion 27, forexample. No attempt is made herein to illustrate details of mounting orbearings, inasmuch as conventional mechanical elements and connectionsmay be employed therefor. It will be seen in FIG. 1 that a relativelysmall objective lens 21 may be employed in this particular embodiment-ofthe invention, with the slit aperture 23 disposed immediately behind thecenter of such lens. It will be apparent to anyone skilled inphotographic techniques that, if the distance between objective 21 andtransducer 14 is small, a coordinated rotational motion of the entirecamera about the transducer will be required in order to keep thetransducer output screen in view: If the distance is relatively large,no such coordinated rotation is required.

Now with regard to the accomplishment of depth-perception radiography,it is to be appreciated that the planar transducer emits light having anintensity at each point of the output face proportional to the intensityof incident radiation on the corresponding point of the input face. Thepresent invention operates to obtain instantaneous images upon thephotographic medium which are displaced laterally, rather thansuperposed upon one another, by varying the angle that a light beamcoming from a narrow slit at the objective impinges upon thephotographic medium in synchronization with a changing view of thesubject on the transducer output screen resulting from the subjectrotating in the path of a radiation beam falling on the input screen ofthe transducer.

Further to the foregoing, it will be noted that with the objective 21and aperture 23 disposed to the left in FIG. 1, so that the aperturemight appear at the point 31, for example, light rays 32- transmittedthrough the aperture will impinge upon each lenticulation 17 at someparticular angle from the point 31. Such light at each lenticulation isthen focused into a single line on the emulsion behind thelenticulation. As the objective and aperture are moved laterally, theangle at which light is directed upon the lenticulations continuallychanges; and, thus, the position of the line behind the lenticulation ischanged. This continues until the aperture is disposed at the right ofFIG. 1, for example at point 33, wherein it will be seen that light raysimpinge upon the lenticulations of the film at a much different anglethan when they emanated from the aperture position 31.

Thus, lateral movement of the aperture and objective in this embodimentof the present invention provides for successive recording of separateand'distinct lines behind each lenticulation, and this lateral motionmay be accomplished in either a continuous or stepwise fashion. Withrotation of the subject 12 during lateral motion of the aperture andobjective, there are, thus, recorded upon the film a plurality ofseparate images of the subject in the'form of successive lines behindindividual lenticulations. Only a minute portion of the film emulsion isexposed at any one aperture position, i.e., only a thin, vertical lineof the emulsion is exposed behind each lenticulation for each apertureposition; and successively different aperture positions laterally acrossthe apparatus expose successive, but separate, lines behind eachlenticulation.

As a consequence of the foregoing, the present invention provides forretrieval of the separately recorded images, for a viewer will see" adifferent image at each different angle of viewing of the developedfilm. While lenticulations serve to focus incident light into a linebehind each lenticulation with the position of the line being determinedby the angle of incident light, these lenticulations also serve toexpand one individual line behind each lenticulation to cover the entirelenticulation surface to a viewer, with the line exposed beingdetermined by the angle of viewing. The invention, therefore, is seen toprovide for successive recording of individual retrievable images.

It is to be appreciated that lateral translation of the position fromwhich the transducer light is focused upon the photographic medium issynchronized in some manner with the rotational motion of the subjectl2.-ln accordance with prior art teaching, the relative movements may bedirectly synchronized for a true perspective depiction of the subject,or, alternatively, variations in relative movements may be made toeither emphasize or minimize depth perception. It is to be further notedthat the invention provides for the utilization of an elongated, narrowslit aperture for the transmission of light from the objective 21 ontothe photographic medium. Of course, the objective lens is disposed inappropriate position to focus light from the transducer onto thephotographic medium. Of particular importance herein is the utilizationof the elongated slit aperture to thereby minimize the lateral extent oftransducer viewing while maximizing the amount of light that can betransmitted to the photographic medium. This serves to sharply focus thesuccessive images upon the photographic medium in juxtaposition, so thatthey may be later individually retrieved by different angular viewing ofthe developed film through the displacement grid or lenticulations 17without confusion between separate images. This furthermore provides formaximization of the light transmittal to the film so that goodresolution is obtained. Apparently various prior art workers in thefield have found it necessary to employ wide openings, in order to focusa sufficient amount of light on the film to develop a picture therefrom;and, even though such a procedure is feasible where a depth-perceptionpicture is to be taken of a three-dimensional object illuminated withvisible light, as opposed to the case herein where a picture is to betaken of a shadow" which has been cast by a three-dimensional objectonto a two-dimensional surface, it makes it impossible to avoidintegrating the successive instantaneous images, and, therefore,prevents their separable retrievability. Furthermore, the presentinvention employs a highly efficient transducer 14 which not onlyfaithfully transduces'incident radiation into emergent light, but,additionally. intensifies the energy of emergent light. Reference isagain made to my above-identified copending patent application for ahighly advantageous transducer that may be employed in this respect.

Reference is now made to FIG. 2 illustrating an alternative embodimentof the present invention, and wherein there is illustrated a transducer14 having an output face 41 from which photographic light emanates inproportion to radiation incident upon an entrance face 42 thereof. Thisrelationship between incident radiation and emergent light is directlyproportional for each point along the surface of the transducer. Aphotographic medium 43 is illustrated to include a film 44 which hassuitable refracting lenticulations embossed on the surface toward thecamera objective and a sensitive emulsion on the opposing surface. Thisembossed displacement grid may, for example, comprise elongatedtransparent lenticula tions of cylindrical form as shown. In thisembodiment of the present invention a housing at 47 removably supportsthe photographic medium 43, and carries at the front thereof anobjective lens 48 displaced from the photographic medium an appropriatedistance, so that light incident upon the objective lens is focused uponthe photographic medium. Additionally, the invention, as illustrated inH0. 2, includes a laterally moveable plate 49 having an elongated slitaperture 51 therein. This plate may be mounted in suitable bearings 52or the like, so as to be sealed in lighttight relation to the housingand yet moveable to the walls thereof. Appropriate means exteriorly ofthe housing may be employed for lateral translation of the plate 49 ineither a continuous motion or in stepwise fashion. Mechanical motionmeans for the plate 49 are not illustrated, inasmuch as a wide varietyof conventional arrange ments may be utilized for this purpose. Anymotion of the subject will cast changing shadows on the transducer inputso as to produce successive images on a single film. in this way it ispossible to record motion or articulation of the subject on a singlepiece of film so that the motion may be reenacted by the viewer at willby visually scanning the film from different angles. For instance, amanic" of the heart action of a subject might be x-ray photographed on asingle film format and later reviewed by rotating the film about alenticular axis in front of the viewer. In this embodiment of thepresent invention, it will be seen that the intensity of radiationincident upon a point 61 of the transducer will vary as the subject 12is rotated, dependent upon the path length of radiation through thesubject and the chemical or physical properties of the subject.Consequently, the intensity of light emitted from a point 61' on theexit face of the transducer 14 will vary in direct relationship to theintensity of incident radiation at the point 61. A plate 49 is movedlaterally across the objective lens, either in front or in back thereof,so that only that portion of the light emanating from point 61' whichpasses through the aperture slit 51 when it is in a given position willreach the refracting lenticulation, and the angle at which it isincident upon the lenticulation will be determined by the position ofthe aperture slit at that moment, which, in turn, will influence theamount of lateral displacement of the strip image on the sensitiveemulsion. It will thus be seen that as the slit aperture 51 of the plate49 is moved transversely across the objective 48, the light from thetransducer exit surface which is able to pass through the aperture slitwill be focused on the lenticulated surface of the film by the cameraobjective. Each lenticulation will, in turn, focus the light fallingthereon to a strip of the emulsion behind the respective lenticulationsand displaced laterally from the medial zone, depending upon the angleat which the light from the slit strikes the lenticulation.

The maximum angle of incidence of light from the slit aperture to thelenticular surface is established by conventional geometric opticprinciples, which are well known, relating the focal distance of theobjective, its magnification ratio, diameter of the objective andfraction of the cylinder arc composing each lenticulation, so that theemulsion area behind each lenticulation is completely filled and thereis no overlap of the exposed zone from one lenticulation to the nextadjacent one.

A picture taken by the above-described process and/or with theabove-described embodiments of the present invention in which thesubject is rotated comprises a plurality of adjacent interleaved imageportions upon the photographic medium which, when viewed biocularly,produces a three-dimensional effect. inasmuch as the line-of-sight fromeach eye of a viewer is incident upon the photographic medium, orlenticulations of the screen or grid upon the film at slightly differentangles, each retina will, thus, receive slightly different aspects ofthe original subject because of the rotation of the subject while thepicture sequence is being recorded at a continuously changing angle ofincidence. The two slightly different images are fused in the visualcortex enabling the observer to perceive a three-dimensional object bythe same mechanics as if the three-dimensional object were actuallypresent. As a supplement to the phenomena of retinal disparity notedimmediately above, a second effect further enhances the perception ofdepth. As either one or both eyes of an observer scans the photographicmedia from differing viewpoints, there results a changing parallax forcorresponding points, so that it is possible for the viewer toapparently see the photographed object from different angles; and, infact, to actually see around portions of the subject.

It is also possible to accomplish a portion of the objectives of thepresent invention in a manner superficially similar to prior artapproaches to the problem in that there is provided a synchronousrotation of the film about an axis parallel to those of thelenticulations while providing for relative rotation of subject and thecombination of source and transducer. This arrangement has thedisadvantage of requiring rather complex linkage arrangements, such asillustrated and described in the above-noted Bonnet patent; however, thepresent invention does provide for production of suitable radiographstherefrom by the utilization of a narrow aperture for directing lightfrom the objective onto the photographic medium. This, together with theemployment of an efficient transducer which not only faithfullyreproduces incident radiation in the form of photographic light, but,furthermore, intensifies the light, overcomes the difficulties of theprior art in directing sufl'lcient light upon the photographic medium toproduce sharp, readable pictures. Referring to FIG. 3 there isillustrated a rotativc system. The embodiment of HO. 3, in brief,includes the radiation source 11 disposed on one side of a subject l2and emitting penetrating radiation 13 of the type described above. Atransducer 14 disposed on the opposite side of the subject 12 from thesource 11 produces photographic light, in general, indicated by the rays71 which are focused by an objective lens 72 through a slit aperture 73in a fixed plate 74. A photographic medium 76, of the type generallydescribed above, is disposed on the opposite side of the plate 74 fromthe objective 72, and is mounted for angular rotation about an axisnormal to the paper and lying in the film plane parallel to the axis ofthe lenticulations. Bellows, or the like, 77 interconnect thephotographic medium in plate 74, so as to maintain a lighttightenclosure between the plate and photographic medium. I! is to beappreciated that in all embodiments of the present invention extraneouslight is excluded from the embodiments hereof between the transducer 14and photographic end of the apparatus by means not shown. In thisembodiment suitable pivoting or rotational means and linkage 78 areprovided interconnecting the photographic medium 76 and the subject 12,or a table or the like, 78, upon which same may be mounted. Reference isagain made to the prior art for suitable pivotable linkage that may beemployed in this respect; and, it is noted that under certaincircumstances it is necessary for the photographic medium and subject tobe rotated in opposite directions in order not to reverse theradiograph. While this embodiment of the present invention, in manyrespects, resembles prior art apparatus for depth-perceptionradiography, it is particularly noted that a critical and essentialdifference stems from employing a very narrow aperture so as to providea continuous sequence of views of the subject, which views areprogressively changing with time, to be recorded sequentially withoutoverlap on the emulsion. This may be alternatively stated as limitingthe aperture width, laterally of the lenticulations, so that theinstantaneous image thereof focused on the emulsion has a width that isa small fraction of the width of the lenticulation. A further advanceafforded by this invention lies in the elongation of the apertureaxially of the lenticulations so as to maximize the amount of lightavailable for exposing film. In this manner it is possible to produce acontinuous time sequence of views of the subject while it is beingrotated in a beam of penetrating radiation so that the two eyes may at alater time, but simultaneously, view slightly different aspects of thesubject and satisfy the condition of retinal disparity. Also, if thepair of eyes are moved so as to observe the photograph from a differentangle, a wholly new pair of views are presented to the respectiveretinas. This changing parallax efi'ect distinguishes depth perceptionfrom conventional stereoscopy.

Certain portions of the present invention are worthy of particular noteand emphasis, particularly with regards to possible variations therein.It is, thus, specifically noted that the photographic medium issusceptible to a wide variation in configuration. It is not necessarythe photographic medium be planar; but, instead, it may, for example, becylindrical, and this configuration finds particular application invarious circumstances. Furthermore, the displacement grid or screen uponthe front surface of the film of the photographic medium may take a widevariety of configurations as generally described above. Particularly inthe instance wherein the displacement grid comprises closely spacedspherical lenses, it is noted that relative movement of a circular lightaperture should be circular in a plane perpendicular to theline-of-sight of the apparatus, rather than in a single lateraldirection, as described in connection with particular preferredembodiments of this' invention. It is, additionally, noted that theradiant energy employed to penetrate the subject may take a variety offorms such as sonic, ultra-sonic, visible light, ultra-violet,infra'red, radio frequency, x-ray, gamma ray, nuclear particles and thelike. it is only required that this radiation be of such a nature as tobe partially absorbed, attenuated, diffused, dissipated or altered inpassage through the subject in proportion to the path length traversedand the chemical or physical properties thereof.

There has been described above method and apparatus for producingdepth-perception photographs of three-dimensional subjects which areopaque to visible light, which is highly advantageous in the field ofradiography, not only in improved results, but, also, in simplificationof prior art approaches to the problems involved in this field. Thepresent invention is particularly advantageous in the field of medicineand the results obtainable herewith allow the radiologist to look aroundas well as through the discontinuities within the subject, much asthough a glass model of the subject were being examined. Although thepresent invention has been described above in connection with particularpreferred steps in the process hereof and in terms'of a particularpreferred embodiment of the apparatus of the present invention, it isnot intended to limit the invention to the exact terms of thedescription or details of illustration. Instead, reference is made tothe appended claims for a precise delineation of the true scope of thepresent invention.

iclaim:

l. A process of depth-perception radiography comprising the steps of:

a. irradiating a subject with a penetrating radiation that has theintensity thereof affected in passage through the sub ject;

b. transducing radiation emerging from the subject into photographiclight emanating from a plane surface and proportional in intensity toincident radiation at a corresponding point on the opposite side of thesurface;

c. focusing said photographic light from step I; through a smallaperture upon a photographic medium having a displacement grid on thefront surface thereof;

d. casting a changing radiation pattern of the subject upon atransducing plane of step b by relatively rotating the subject and thecombination of the radiation source and transducer which are fixed withrespect to each other; and

e. changing the angle of incidence of light on said photographic mediumin synchronism with step d, to focus a plurality of images ininterleaved portions upon said photographic medium for individualretrieval.

2. The process of claim 1 further defined by said displacement gridhaving transparent cylindrical lenticulations, and said rotation beingabout an axis parallel to the axis of said lenticulations.

3. The process of claim 2 further defined by changing the angle ofincident light by laterally moving a narrow, elongated slit alignedparallelto the axes of said lenticulations.

4. The process of claim! further defined by moving said slit apertureacross a large objective lens focusing light upon said photographicmedium.

5. The process of claim 3 further defined by moving a small objectivelens and said narrow, elongated slit aperture together laterally of saidlenticulations.

6. The process of claim 2 further defined by rotating both saidphotographic medium and the subject in synchronism while focusing lighton the photographic medium through a narrow elongated slit parallel tosaid lenticulations.

7. The process of depth-pcrception radiography as set forth in claim 1further defined by continuously changing the radiation pattern of thesubject in step d whereby continuously va in im es are focused u n saioto i Q. The pit xess of clepth-pei eptid n r t tdiogi g li; s i f r irth in claim 1 further defined by changing the radiation pattern of thesubject upon the transducer plane in discrete increments in step dwhereby successive juxtaposed images are focused upon the photographicmedium.

9. Apparatus for depth-perception radiography comprising:

a. a source of penetrating radiation;

b. means for mounting a subject in front of said source;

c. a transducer disposed on the opposite side of said subject from saidsource and producing photographable light from incident radiation;

d. a photographic medium having a displacement grid on a front facethereof;

e. an objective lens focusing light from said transducer on the frontface of said photographic medium;

f. means maintaining the source and transducer in fixed relationrelative to each other and relatively rotating same with respect to saidsubject; and

g. means scanning a narrow aperture across said photographic medium todirect light from different angles thereon to record an image havingjuxtaposed and separable interleaved image portions.

10. The apparatus of claim 9 further defined by said displacement gridcomprising cylindrical lenticulations parallel to said slit, and themeans of g including a plate with a slit therein and an objective lensover said slit and means moving both plate and leris laterally acrosssaid lenticulations.

11. The apparatus of claim 9 further defined by said displacement gridhaving parallel transparent lenticulations on a light intercepting facethereof, said relative rotation being provided about an axis parallel tothe axis of said lenticulations and said aperture having a width lessthan that effecting exposure of one-half of the photographic mediumbehind each lenticulation.

12. The apparatus of claim 9 further defined by the medium d comprisingparallel cylindrical transparent lenticulations upon alight-intercepting face of photographic emulsion, and said narrowaperture having a limited maximum dimension laterally of thelenticulationsso that an instantaneous image thereof focused on saidemulsion behind each lenticulation has a width limited to a smallfraction of the width of the lenticulation.

13. The apparatus of claim 12 further defined by said narrow aperturebeing elongatedparallel to the axes of lenticulations to maximize lightfocused on said photographic medium.

14. The apparatus of claim 9 further defined by the means g includingmeans defining a narrow aperture between said objective lens and saidphic meditun and means rotating said photographic medium a! and means bmounting a subject in synchronism while maintaining the remainder of theapparatus fixed. with respect thereto for directing light from differentangles onto said photographic medium.

1. A process of depth-perception radiography comprising the steps of: a.irradiating a subject with a penetrating radiation that has theintensity thereof affected in passage through the subject; b.transducing radiation emerging from the subject into photographic lightemanating from a plane surface and proportional in intensity to incidentradiation at a corresponding point on the opposite side of the surface;c. focusing said photographic light from step b through a small apertureupon a photographic medium having a displacement grid on the frontsurface thereof; d. casting a changing radiation pattern of the subjectupon a transducing plane of step b by relatively rotating the subjectand the combination of the radiation source and transducer which arefixed with respect to each other; and e. changing the angle of incidenceof light on said photographic medium in synchronism with step d, tofocus a plurality of images in interleaved portions upon saidphotographic medium for individual retrieval.
 2. The process of claim 1further defined by said displacement grid having transparent cylindricallenticulations, and said rotation being about an axis parallel to theaxis of said lenticulations.
 3. The process of claim 2 further definedby changing the angle of incident light by laterally moving a narrow,elongated slit aligned parallel to the axes of said lenticulations. 4.The process of claim 3 further defined by moving said slit apertureacross a large objective lens focusing light upon said photographicmedium.
 5. The process of claim 3 further defined by moving a smallobjective lens and said narrow, elongated slit aperture togetherlaterally of said lenticulations.
 6. The process of claim 2 furtherdefined by rotating both said photographic medium and the subject insynchronism while focUsing light on the photographic medium through anarrow elongated slit parallel to said lenticulations.
 7. The process ofdepth-perception radiography as set forth in claim 1 further defined bycontinuously changing the radiation pattern of the subject in step dwhereby continuously varying images are focused upon said photographicmedium.
 8. The process of depth-perception radiography as set forth inclaim 1 further defined by changing the radiation pattern of the subjectupon the transducer plane in discrete increments in step d wherebysuccessive juxtaposed images are focused upon the photographic medium.9. Apparatus for depth-perception radiography comprising: a. a source ofpenetrating radiation; b. means for mounting a subject in front of saidsource; c. a transducer disposed on the opposite side of said subjectfrom said source and producing photographable light from incidentradiation; d. a photographic medium having a displacement grid on afront face thereof; e. an objective lens focusing light from saidtransducer on the front face of said photographic medium; f. meansmaintaining the source and transducer in fixed relation relative to eachother and relatively rotating same with respect to said subject; and g.means scanning a narrow aperture across said photographic medium todirect light from different angles thereon to record an image havingjuxtaposed and separable interleaved image portions.
 10. The apparatusof claim 9 further defined by said displacement grid comprisingcylindrical lenticulations parallel to said slit, and the means of gincluding a plate with a slit therein and an objective lens over saidslit and means moving both plate and lens laterally across saidlenticulations.
 11. The apparatus of claim 9 further defined by saiddisplacement grid having parallel transparent lenticulations on a lightintercepting face thereof, said relative rotation being provided aboutan axis parallel to the axis of said lenticulations and said aperturehaving a width less than that effecting exposure of one-half of thephotographic medium behind each lenticulation.
 12. The apparatus ofclaim 9 further defined by the medium d comprising parallel cylindricaltransparent lenticulations upon a light-intercepting face ofphotographic emulsion, and said narrow aperture having a limited maximumdimension laterally of the lenticulations so that an instantaneous imagethereof focused on said emulsion behind each lenticulation has a widthlimited to a small fraction of the width of the lenticulation.
 13. Theapparatus of claim 12 further defined by said narrow aperture beingelongated parallel to the axes of lenticulations to maximize lightfocused on said photographic medium.
 14. The apparatus of claim 9further defined by the means g including means defining a narrowaperture between said objective lens and said photographic medium andmeans rotating said photographic medium d and means b mounting a subjectin synchronism while maintaining the remainder of the apparatus fixedwith respect thereto for directing light from different angles onto saidphotographic medium.